Williams, who has battled injuries throughout his three-year NFL career, was tackled by safety Chris Harris with approximately three minutes left in the first half. Williams fell awkwardly and grabbed his right leg just below the knee following contact.

The patellar tendon helps hold the kneecap in place. An injury to the tendon can have significant impact on an athlete's ability to jump or accelerate, even after it heals following surgery. Williams is expected to see renowned orthopedic surgeon Dr. James Andrews in Birmingham, Ala., on Monday, according to a member of Williams' family.

Tampa Bay coach Jon Gruden declined to discuss any specifics about the injury. However, both Williams and quarterback Jeff Garcia acknowledged the seriousness of the injury. In addition, the entire Bucs team came onto the field as Williams was carted off.

"I don't know what it is, all I know is it's severe," said Williams, who was in the locker room briefly after the game.

"I'm sure that Cadillac knew at that point his season was over," said Garcia, when asked about the team's gesture. "We just wanted him to know how much we support him."